type-case-woes.scala

/**
 * Pretend type-case doesn't exist in Scala. We know nothing about `A` and `B`,
 * so there's only thing we can do here: apply `f` to `a` and return the result.
 */
def foo[A, B](a: A)(f: A => B): B = ???

/**
 * Now with type-case. Since the implementation can look at the type of `a` we
 * have no idea what it might be doing.
 */
def foo[A, B](a: A)(f: A => B): B = a match {
  case i: Int => f(i * 2)
  case c: Char if c >= 'a' && c <= 'z' => f(('a' + (c + 13 - 'a') % 26).toChar)
  case x => f(x)
}